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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Operation Regime Analysis of Conduction Cooled Cavities through Multi-Physics Simulation

Euclid Techlabs in collaboration with Fermilab IARC (Batavia, IL) is developing industrial superconducting 10MeV electron linac [1, 2]. Cryocoolers are to be used for cooling instead of liquid helium bath to simplify the linac infrastructure [3]. The cavity linked to commercially available cryo-cooler cold head [4, 5] through highly conductive aluminium (AL) strips. However, this solution raises a problem of contact thermal resistance. This paper shows some results of Comsol multyphysics simulations of the cavity cooling by AL strips. Some insight was obtained on the acceptable range of contact resistance. Operation regimes were obtained at different accelerating gradients and cavity temperatures. The results of simula-tion are presented and discussed.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Multi-Physics Simulation of The TRIGA Reactor

In nuclear engineering, the description of phenomena occurring in the core involves a coupling between neutronic and thermal hydraulics through the so called reactivity or thermal feedback. In water cooled reactor, thermal feedback and temperature coefficients of reactivity are important, when temperature changes, microscopic cross sections change as well impacting directly the neutron flux and so the thermal power. Other feedback, such as the variation of the macroscopic cross section due to a modification of the density can also have a significant impact on the core performance of the reactor. Those reasons were naturally leading in the development of coupling method in order to predict correctly the behaviour of the core in normal operation and accidental situation. This work describes the coupling scheme developed for the description of the TRIGA mark II reactor at JSI. The demonstration case presented here, the reactor is operating in steady state configuration at several power levels. The aim of our calculation was, for a given thermal power of the reactor, to numerically reproduce fuel temperature value monitored during reactor operation. The expected impact of the control rod on the neutron flux distribution was also verified. The predictions of the coupling scheme seem to be correct according to the few temperature measurements available and the expected neutron flux behaviour expecting from a control rod motion. We are considering precise measurement of the fuel temperature at more positions but also in the coolant channels between the fuel elements to complete the experimental validation phase. An upgrade of the coupling scheme into the transient mode is also considered to observe self-stabilisation of the power level, after a control rod perturbation, due to the negative temperature reactivity coefficient of the fuel. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗